Check gauges on 2002 Chevrolet Trailblazer

just noticed that my check gauges light would go on then cut off back and forth. I looked at my gauges and noticed that my oil pressure gauge will be fine then fall then jump back to normal. What do you think?

Asked by for the 2002 Chevrolet Trailblazer
i would start by changing the oil pressure switch on the engine.
When I am idleing it drops , then when I give the gas it jumps back to normal ...... Is an oil pressure switch expensive usually?